Grinding disk



Sgpt. 29, 1953 P. K. FULLER 2,653,428

GRINDING DISK Filed April 10, ,1952

IN V EN TOR. Paul K. Fuller A7 r ORIVE Y3 Patented Sept. 29, 1953 UNITEDSTATES" PATENT" OFFICES-" camp re DISK Paul K. Fuller, Rocky River, OhioApplication April 10, 1952, Serial Nb. 281,592

This invention relates to improvements in grinding disks and moreparticularly to a pattern formed in the grinding area.

One of the objects of the present invention is to provide a toughflexible grinding disk generally circular in form having a smoothcentral area where the disk is secured to a backing plate and havingsmooth non-abrasive paths extending generally radially outwardly throughthe grinding area of the disk, these smooth paths bending alternatelyclockwise and counterclockwise around the disk, so that when the disk isro tated and applied to a piece of work, the edges of said smooth pathsprovide draw cuts to the work alternately radially inwardly and radiallyoutwardly.

Other objects and advantages of my invention will be apparent from theaccompanying drawings and description and the essential features thereofwill be set forth in the appended claim.

In the drawings,

Fig. 1 is a top plan view of a grinding disk embodying my invention;

Fig. 2 is a fragmental sectional view greatly enlarged taken along theline 2-2 of Fig. 1;

Fig. 3 is a small side elevational view of a grinding disk mounted upona backing plate and applied to a piece of work, while Fig. 4 is a topplan view of a grinding disk similar to Fig. 1 but showing a slightlydifferent pattern of the smooth paths extending through the grindingarea.

Grinding disks of the type here described are usually about seven ornine inches in diameter and these disks are often used on yieldablesupporting pads mounted on a rigid backing member or the disks may bemounted directly upon a flexible backing plate so that the abrasive diskmay yield somewhat as it is applied to the Work. A common manner ofmounting these disks is shown in Fig. 3 where a grinding disk 10 ismounted upon a backing plate H which in turn is rotatable with a shaftl2 by which the grinding disk is applied to the work, here indicated at13 as being two plates welded together and the grinding disk is utilizedto smooth away the weld I 4 prior to applying a finish to the smoothsurface. Other uses of grinding disks of the kind here shown are wellknown and require no further amplification.

The structure of the disk itself may vary greatly within the scope of myinvention. I have chosen to illustrate here a grinding disk like thatdisclosed and claimed in the copending application of Aaron J. Teller,Serial No. 270,163, filed 1 Claim. 01. 51-195) February 6, 1952, for

2 Grinding Disk Construction. Referring to Fig. 2, the above-mentioned-patent application describes a tough flexible backing sheet I5 of fiberboard or the like approximately s s inch thick. To this backing sheet isapplied a base coat [6 by dipping or the like. On top of this base coatthere is provided a making coat I! of polymerized furanprocessedaccording to the above-mentioned Teller patent application soas to give a tough but yielding base in which the abrasive particles l8are held. The abrasive particles may be any suitable material but Iprefer aluminum oxide or silicon carbide or sharp particles of steel. ANo. 24 grit of aluminum oxide gives very good results. Over the makingcoat I! and the abrasive particles IB there is formed a cover coat I 9which may also be of polymerized furan so treated that it is slightlymore brittle than the coat I! but is highly resistive to thetemperatures generated during a grinding operation.

My invention does not consist in the particular nature of the abrasivecoating applied to the backing sheet but rather to the pattern formed bythe abrasive material thereon.

Referring to Fig. 1, the abrasive disk H] has a smooth central area 20,in the center of which there may be provided an opening 2| for securingthe disk to the backing plate as by means of the bolt 22 as shown inFig. 3. Outside of the central area 20 is the grinding area 22. Throughthis grinding area I provide smooth non-abrasive paths 23a and 23bextending generally radially outwardly through the grinding area butbending somewhat out of the radial path as shown in Fig. l. The path 23abends clockwise, then the path 23b bends counterclockwise and so onalternately around the disk. A simple way of providing these paths is toform the making coat l1 in the pattern of Fig. 1 on top of the base coatl6 leaving the paths 23a and 23b free of the making coat l1. Then whenthe abrasive particles l 8 are sprinkled upon the disk, they adhere onlyto the areas between the smooth paths 23a and 23b.

It results from the construction shown in Figs. 1 and 2 that when thedisk I0 is rotated and applied to a piece of work, the generallyparallel edges of the path 23a apply draw cuts to the work. The outerportion of the path 23a indicated at 24, will provide a draw outgenerally radially outwardly when the disk I0 is rotating in thedirection of the arrow shown in Fig. 1. The next following edges 25 ofthe outermost portion of the path 23b will provide draw cuts radiallyinwardly. This is repeated alternately around the periphery of the disk.On the other hand, the inner portion 26 of the path 23a will have edgesproviding dr-aw cuts radially inwardly while the following edges in theportion 21 of the path 231) will provide draw cuts extending radiallyoutwardly. I find that this application of draw cut alternately radiallyinwardly and radially outwardly around the entire disk gives a patternof crissorossing scratches of very fine character which resultsqina"very smooth piece of'work.

In the modification of Fig. 4 everything is exactly like that describedin connection with Fig. 1 except that here the paths 28a and wheresmooth curves rather than angularly related as in Fig. 1. It will benoted that draw.'-cuts=.alternately radially inwardlyandradiallyoutwardly around the disk will be provided asthe diskisapplied to the work.

It will be noted thatrin both forms of my in-.vention=-as-.shownsindiigu 1-;andeFig. 4, the-.smooth gpaths==23a i23band 28:1,:2817 providechannels stltrr ngh e'which eairs, isthrownscentrifugally outwardly during the rotation of the-.disk l0. This.eresultsina coolingaction-ruponethe abrasive disk eandiatzthe same-time:keeps. thersmootl'r paths 2 3 a, 13b, 28a,- and 28b cleartof.-.abrasive particlesv or ,portions. freed from the. work by theabrasive par- -:ticles. Since the.smooth-. paths are .open at theperiphery of .thedisk, thesair-ahas free escapefrom ,the; edges.ofithe'. diskrandsany particles. collecting in the smooth paths areeasily thrown outwardly and cleared from the disk at the peripheral edgethereof.

What I claim is:

An abrasive disk comprising :a tough flexible backing sheet of circularform, there being a smooth central area surrounded by a grinding area,said grinding area comprising abrasive particles bonded to said backingsheet, there being asmooth' non-abrasive paths extending outwardlythrough said grinding area from a" zone within said grinding area spacedoutwardly from said -smooth central area to the periphery of said disk,esaidsmooth paths bending alternately clockwise and counterclockwisearound said disk, whereby, r-whensaid zdisk is rotated and applied to apiece of.work, the edges of said smooth paths provide -draw cuts to'thework alternately radially inwardly and radially outwardly.

tPAULs'KhflULLER.

References Citedlin .the,file of ;this patent .UNITED STATES 1 PATENT S

